(1) Field of the Invention
The present invention is related to a maintenance step for a helicopter, said maintenance step comprising the features of claim 1. The present invention is further related to a helicopter with such a maintenance step, said helicopter comprising the features of claim 15.
(2) Description of Related Art
Maintenance steps are generally present on all helicopters and can be provided in different numbers on the helicopters dependent e.g. on an underlying helicopter size. For instance, three maintenance steps per side are provided on the H135 and H145 from Airbus Helicopters and more steps can be provided e.g. on the NH90 from Airbus helicopters.
In general, maintenance steps are adapted to allow maintenance crew members to get in a position where they can fulfil required maintenance tasks, especially checks at the helicopter's engines and main gear box. Thus, the maintenance steps must be suitable to provide access to respective upper decks of helicopters so that they are always located outside of a helicopter, namely in a lateral shell of the helicopter's fuselage.
More specifically, maintenance steps are usually part of a fuselage of a helicopter and can be visible to the outside, i.e. distinguishable from the fuselage. However, they are preferably hidden and retracted, i.e. made flush to an outer surface of the fuselage, in flight operation of the helicopter.
An exemplary maintenance step on a fuselage of a helicopter comprises a trap-like single step that is pivotally mounted to a support element and connected to a rotatable stirrup, which is storable on the support element. However, due to the dimensions of the rotatable stirrup, the trap-like single step must be designed relatively large such that the trap-like single step can be stored thereon. This, nevertheless, results in additional weight, costs and integration problems of the maintenance step. Furthermore, this maintenance step cannot be used for an undercut in a lateral shell of a helicopter's fuselage, as the support element cannot be adapted thereto in a suitable manner.
The document US 2011/0272524 A1 describes an integrated maintenance step on a fuselage of a helicopter. This maintenance step comprises a casing that is integrated into a lateral shell of the fuselage for access from outside of the helicopter, and a single step that is pivotally mounted in the casing. In other words, the maintenance step is foldable and flush to an outer surface of the fuselage of the helicopter. The term “flush” means that the outer surface is smooth and the maintenance step is integrated into this outer surface such that it is not distinguishable when observed from a predetermined distance.
The document U.S. Pat. No. 8,905,354 B1 describes a foldable step assembly for a helicopter with a housing and a single support member that is hingedly coupled to the housing by means of a shaft. The support member is configured as a step support and a hand hold device and it is adapted to rotate between a stored position and a deployed position. Furthermore, a first locking feature is associated with the support member and a second locking feature is associated with the housing. Moreover, a spring is operably associated with the support member and the housing such that the spring biases the first locking feature towards the second locking feature.
However, the above described maintenance steps and step assemblies only comprise foldable single steps that are folded, i.e. turned around a single axis, in order to provide a step for getting access to an upper deck of a helicopter. This kind of single step is, nevertheless, only usable in a straight, middle area of a lateral shell of a helicopter's fuselage. In case of an undercut in the lateral shell, e.g. close to a bottom shell of the helicopter's fuselage, it is not possible to use such a single step without major impact on style, loft and integration in the helicopter. In particular, in case of such an undercut in the lateral shell a single step that is arranged close to a bottom shell of the helicopter's fuselage can simply be unusable or at least not safely or ergonomically usable.
If, however, no other technical solution exists to integrate a maintenance step on a lowest position in an undercut area, i.e. close to a bottom shell of the helicopter's fuselage, so that only a maintenance step in a higher position can be provided, an extra device such as e.g. a small ladder that is placed in front of the helicopter would be necessary to grant access to the maintenance step in the higher position. This is, however, not acceptable if quick access to an upper deck of the helicopter without additional devices should be enabled.